Contact tracing systems and methods for tracking of shipboard pathogen transmission

ABSTRACT

Contract tracing systems and methods for infectious disease tracking are disclosed. An infectious disease tracking system includes a plurality of user devices, each user device configured to detect, using a wireless communication module, a signal emitted by another one of the plurality of user devices. The user device can determine that a strength of the signal exceeds a predetermined event initiation signal strength threshold corresponding to a physical proximity between users of the devices and can store a contact tracing event record in response to determining that the strength of the signal exceeds the predetermined event initiation signal strength threshold. The user device can transmit the contact tracing event records to a data center where they can be stored and used to identify close contacts when an index case of an infectious disease is identified.

CROSS-REFERENCE TO RELATION APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/195,489, filed Mar. 8, 2021, titled “CONTACT TRACING SYSTEMS ANDMETHODS FOR TRACKING OF SHIPBOARD PATHOGEN TRANSMISSION,” which claimsthe benefit of U.S. Provisional Application Ser. No. 62/987,343, filedMar. 9, 2020, titled “CONTACT TRACING SYSTEMS AND METHODS FOR TRACKINGOF SHIPBOARD PATHOGEN TRANSMISSION,” both of which are incorporated byreference herein in their entirety.

BACKGROUND Technological Field

The present application relates to systems and methods for shipboardcontact tracing upon identifying that a guest of a current or a priorvoyage is an index case having a communicable disease.

Background

Contact tracing is the process of identifying persons who may have comeinto contact with an infected person (“contacts”) and subsequentcollection of further information about these contacts. By tracing thecontacts of infected individuals, testing those contacts for infection,treating the infected and tracing their contacts in turn, public healthsystem seek to reduce and halt the spread of infectious disease within apopulation. Contact tracing can be performed for many different types ofinfectious diseases, including vaccine-preventable andhighly-transmissible infections like measles, various forms ofgastroenteritis (for example, norovirus), and novel infections (forexample, COVID-19, SARS-CoV, and SARS-CoV-2).

SUMMARY

In a first aspect of the present technology, an infectious diseasetracking system for a cruise ship comprises a plurality of user devices,each user device comprising a wireless communication module, one or moreprocessors, and memory storing computer-executable instructions. Whenexecuted by the one or more processors, the instructions cause the oneor more processors to at least detect, using the wireless communicationmodule, a signal emitted by another one of the plurality of userdevices; determine that a strength of the signal exceeds a predeterminedevent initiation signal strength threshold; store, in the memory, acontact tracing event record in response to determining that thestrength of the signal exceeds the predetermined event initiation signalstrength threshold; and transmit the contact tracing event record.

In some embodiments, storing the contact tracing event record comprisesstoring an initial contact tracing event data point including at least atimestamp and an identifier of the other one of the plurality of userdevices, updating the contact tracing event record by storing additionalcontact tracing event data points based on subsequent signals receivedfrom the other one of the plurality of user devices, and terminatingstorage of additional contact tracing event data points. In someembodiments, the instructions further cause the one or more processorsto compare strengths of the subsequent signals to an event interruptionsignal strength threshold, and the storage of additional contact tracingevent data points is terminated based at least in part on at least oneof the subsequent signals having a strength below the event interruptionsignal strength threshold. In some embodiments, the storage ofadditional contact tracing event data points is terminated based on thestrengths of the subsequent signals remaining below the eventinterruption signal strength threshold for at least a predeterminedgrace period. In some embodiments, the grace period is 90 seconds. Insome embodiments, the instructions further cause the one or moreprocessors to at least suspend the storage of additional contact tracingevent data points based on a first one of the subsequent signals havinga strength below the event interruption signal strength threshold, andresume the storage of additional contact tracing event data points inresponse to detecting a second one of the subsequent signals having astrength above the event interruption signal strength threshold prior tothe expiration of a predetermined grace period. In some embodiments, theevent interruption signal strength threshold is lower than the eventinitiation signal strength threshold. In some embodiments, the eventinitiation signal strength threshold is a Received Signal StrengthIndicator value of −68 decibel-milliwatts (dBm), and wherein the eventinterruption signal strength threshold is lower than −68 dBm.

In some embodiments, the event initiation signal strength thresholdcomprises a predetermined Received Signal Strength Indicator (RSSI)value. In some embodiments, the contact tracing event record comprises aplurality of contact tracing event data points, each contact tracingevent data point comprising at least a timestamp and an RSSI value. Insome embodiments, the event initiation signal strength threshold is −68decibel-milliwatts (dBm).

In some embodiments, the contact tracing event record indicates at leasta duration of a contact tracing event and an identifier of the other oneof the plurality of user devices or of a user thereof. In someembodiments, the instructions further cause the one or more processorsto modify the contact tracing event record to indicate a close contactbased on the duration exceeding a predetermined close contact timethreshold. In some embodiments, the close contact time threshold is oneof 5 minutes or 15 minutes.

In some embodiments, the wireless communication module of each userdevice is configured to communicate with the wireless communicationmodules of the other user devices using Bluetooth Low Energy (BLE)protocol.

In some embodiments, the system further comprises a plurality ofwireless access points disposed within the cruise ship and configured toreceive the transmitted contact tracing event record. In someembodiments, the plurality of wireless access points are configured tocommunicate with each of the user devices using Bluetooth Low Energy(BLE) protocol. In some embodiments, the instructions cause the one ormore processors to store a plurality of contact tracing event recordsand to transmit a set of most recent contact tracing event records to anindividual wireless access point of the plurality of wireless accesspoints in response to detecting the individual wireless access point. Insome embodiments, each of the plurality of wireless access points is incommunication with a server and configured to transmit the receivedcontact tracing event records to the server. In some embodiments, theserver is configured to store each contact tracing event record in adata store in association with an identifier of the user device thatgenerated the contact tracing event record or of a user thereof. In someembodiments, the server is further configured to store, in the datastore, an association between each contact tracing event record and anidentifier of a second user device identified in the contact tracingevent record or of a user thereof. In some embodiments, the server isfurther configured to identify pairs of contact tracing event recordsgenerated by different user devices corresponding to a same contacttracing event, based at least in part on timestamps included within thepairs of contact tracing event records. In some embodiments, the serveris further configured to perform deduplication based on the identifiedpairs of contact tracing event records. In some embodiments, the serveris further configured at least receive an identification of a useridentified as an index case user of an infectious disease; query thedata store, in response to the identification of the user, to determinea set of close contact users having close contact records associatedwith the index case user; and output a contact tracing resultidentifying the set of close contact users.

In some embodiments, the system further comprises a server and aplurality of wireless access points disposed within the cruise ship,each wireless access point configured to wirelessly receive the contacttracing event records from the user devices and to transmit the receivedcontact tracing event records to the server, wherein the server isfurther configured to at least store the contact tracing event recordsin a data store; receive an identification of a user identified as anindex case user of an infectious disease; query the data store, inresponse to the identification of the user, to determine a set of closecontact users having close contact records associated with the indexcase user; and output a contact tracing result identifying the set ofclose contact users.

In a second aspect of the present technology, an infectious diseasetracking system for a cruise ship comprises a plurality of wirelessaccess points disposed within the cruise ship and a server, eachwireless access point of the plurality of wireless access pointscomprising a communication module configured to detect and identifymobile devices in proximity to the wireless access point, and aprocessor in communication with the communication module, the processorconfigured to cause storage, in a data store, of a location data pointeach time a mobile device is detected. Each location data pointcomprises a timestamp, an association with the wireless access point,and an association with a user corresponding to the mobile device. Theserver is in communication with the data store and is configured toreceive an identification of a first user determined to be an index caseof a disease; determine, based on the timestamps and the wireless accesspoints corresponding to a plurality of location data points associatedwith the first user, a movement profile corresponding to the first user;identify, based on the movement profile, one or more additional locationdata points indicative of a possible contact with the first user, eachof the one or more additional location data points associated with auser other than the first user; and determine, based on the one or moreadditional location data points, a set of second users who may have comeinto contact with the first user.

In some embodiments, the server is further configured to determinemovement profiles corresponding to the second users. In someembodiments, the server is further configured to determine, based atleast in part on the movement profiles corresponding to the secondusers, a set of third users who may have come into contact with one ormore of the second users. In some embodiments, the server is furtherconfigured to generate, based at least in part on the set of secondusers, the set of third users, and a passenger manifest of the cruiseship, a list of passengers who have not come into contact with the firstuser or the one or more other users who have come into contact with thefirst user. In some embodiments, the server is further configured togenerate, based at least in part on the set of second users and the setof third users, a list of passengers to be quarantined.

In some embodiments, each of the mobile devices comprises one or more ofa personal computing device or a wearable electronic device.

In some embodiments, the communication module of each wireless accesspoint is configured to detect and identify mobile devices using one ormore of near Bluetooth, Bluetooth Low Energy (BLE), near-fieldcommunication (NFC), Wi-Fi, radio-frequency identification (RFID), or awireless broadband communication protocol.

In some embodiments, each of the one or more additional location datapoints is identified if the additional location data point is associatedwith the same wireless access point and has a timestamp within athreshold time relative to at least one of the location data pointsassociated with the first user.

In some embodiments, the server is further in communication with animaging system that records images or video of areas of the cruise shipwhere the wireless access points are located. In some embodiments, theserver is further configured to obtain, from the imaging system, animage or video file corresponding to each of the additional locationdata points; and store an association between each image or video fileand the second user associated with the corresponding additionallocation data point. In some embodiments, the imaging system is furtherconfigured to determine facial recognition results based on imagescaptured by the imaging system, wherein the infection control system isfurther configured to identify second users based on the facialrecognition results.

In some embodiments, the system retains the location data points in thedata store for a predetermined retention period. In some embodiments,the predetermined retention period is one month. In some embodiments,the system retains the location data points stored in the data storeduring a first voyage of the cruise ship until at least the end of asubsequent voyage of the cruise ship.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an example of a networked computingsystem comprising a ship-based computing system and a shore-basedcomputing system in accordance with the present technology.

FIG. 2 schematically illustrates an example system for tracking ofshipboard pathogen transmission in accordance with the presenttechnology.

FIG. 3 schematically illustrates an example user device configured fortracking of shipboard pathogen transmission in accordance with thepresent technology.

FIG. 4 is a flow chart illustrating an example algorithm for recordingcontract tracing events in accordance with the present technology.

FIG. 5 is a flow chart illustrating an example method for contacttracing in accordance with the present technology.

DETAILED DESCRIPTION

Contact tracing seeks to disrupt ongoing transmission and reduce thespread of an infectious disease. Contract tracing generally involves thefollowing steps:

-   -   An individual (“index case”) is identified as having a        communicable disease. This case may be reported to public health        authorities or managed by the primary health care provider.    -   The index case is interviewed to learn about the index case's        movements and with whom the index case has been in close contact        within a specific time period of interest.    -   Depending on the disease and the context of the infection,        family members, health care providers, and anyone else who may        have knowledge of the case's contacts may also be interviewed.    -   Once contacts are identified, public health workers contact the        identified contacts to offer counseling, screening, preventative        care, and/or treatment.    -   Contacts may be isolated (for example, quarantined in a hospital        setting or required to remain at home) or excluded (for example,        prohibited from attending a particular location, like a school)        if deemed necessary to control the spread of the infectious        disease.    -   If contacts are not individually identifiable (for example,        members of the public who attended the same location), broader        communications may be issued, such as media advisories.

In cases of novel infectious disease, contact tracing can also generateimportant data on characteristics of the disease, such as infectiousnessand incubation period. Typical forms of contact tracing are timeconsuming, manpower-intensive, and cumbersome. Contact tracing requiresgreat speed and accurate information to be effective, but often resultsin an incomplete or inaccurate list of contacts. One of the mostsignificant drawbacks to typical forms of contact tracing is the time ittakes to identify individuals who may have been in close contact withthe index case.

The present disclosure is directed to systems and methods for rapidcontact tracing on a vessel, such as but not limited to a cruise ship.Embodiments of the present disclosure can be implemented in manydifferent settings, including but not limited to hospitals and otherhealth-care settings, apartment buildings, office buildings, prisons,amusement parks, and entertainment venues, such as athletic arenas andconcert venues. A combination of systems, such as facial recognitionsystems, Bluetooth Low Energy (BLE) systems, and RFID systems, are usedto collect person-specific data for each person that is physicallypresent within a defined space (such as all crewmembers and guests thatare physically present on a particular cruise ship) or is associatedwith a defined population (such as all guests that have embarked on aparticular voyage of a particular cruise ship).

In some examples, this person-specific data is collected for each guestand crewmember from start to finish of a voyage of a cruise ship. Uponidentification of a guest or crewmember as an “index case” having acommunicable disease, a map of the physical location within the definedspace (hereinafter referred to as a “movement profile”) is calculatedfor the index case, using the person-specific data collected for theindex case. A movement profile can include information on the physicallocation of a person within the defined space at all points in time, orfor all points in time for which person-specific data is available.

In some implementations of the present technology, a movement profile isnext calculated for all persons that are physically present within adefined space (such as all crewmembers and guests that are physicallypresent on a particular cruise ship) or are associated with a definedpopulation (such as all guests that have embarked on a particular voyageof a particular cruise ship). These movement profiles can be calculatedusing each individual's person-specific data that has been collectedduring a particular voyage of the cruise ship.

Embodiments of the present disclosure perform rapid contact tracing bycomparing the movement profile of the index case to the movementprofiles of all other individuals of interest. Individuals of interestcan include, for example, all guests and crew members physically presenton a particular cruise ship at a given point in time, all guests andcrew members that embarked on a particular voyage of a particular cruiseship (whether or not those individuals have since disembarked the cruiseship), and all guests and crew members that were embarked on animmediately-preceding voyage of the particular cruise ship. As a resultof comparing the movement profile of the index case with the movementprofile of other individuals of interest, individuals of interest whowere proximate to or came in close contact with (in one example, withina defined number of feet of) the index case are identified as a “closecontact.” Embodiments of the present disclosure include identifyingfurther “close contacts” by comparing the movement profile of anidentified “close contact” to the movement profiles of all otherindividuals of interest. In this way, “close contacts” of an index caseare rapidly and accurately identified in a shipboard context.

The term “close contact” could be defined by medical personnel onboardas well as public health officials to mean 0 to X number of feet,depending on the type of communicable disease. In one non-limitingexample, an individual is deemed to have close contact with an indexcase if the individual came within zero to three feet of the index case.In another non-limiting example, an individual is deemed to have closecontact with an index case if the individual came within zero to sixfeet of the index case. The distance threshold may be selected (e.g., bya medical officer or other crew member) based on specific transmissioncharacteristics of the particular pathogen or disease. The distancethreshold can be selected based on guidance provided by public healthofficials.

In other implementations of the present technology, a movement profileis next calculated for a subset of persons rather than all personspresent within a defined space or associate with a defined population.For example, if the movement profile of the index case indicates thatthe index case was not physically present on Decks 1, 2, and 3 duringthe duration of a particular cruise, a movement profile may not becalculated for individuals who are known to have only been present onDecks 1, 2, and/or 3 during the duration of the voyage.

In some embodiments of the present technology, contact tracing eventsare recorded based on interactions between mobile devices carried byusers (e.g., guests, crewmembers, or any other persons present withinthe defined space or population). For example, each user present withinthe defined space may carry a mobile device such as a dedicated wearabledevice, a smartphone, tablet, or other computing device, or the like.The mobile devices may be configured to detect other mobile deviceswithin a determined proximity (e.g., using any suitable wirelesscommunication protocol such as Bluetooth, Bluetooth Low energy, RFID,Wi-Fi, or the like) and to record contact tracing events based on thedetected mobile devices according to various algorithms as describedherein. In one example, contact tracing events may be recorded and/ordetermined to be “close contacts” at each mobile device when anotherdevice is detected within a predetermined proximity threshold and/or forat least a threshold time (e.g., a close contact time threshold). Insome embodiments, the proximity of another mobile device may bedetermined based on a measurable quantity such wireless signal strength.As will be described in greater detail, suitable algorithms forrecording contact tracing events and determining close contacts may beimplemented so as to avoid or reduce the recording of false positiveclose contacts and/or the failure to record close contacts based onfalse negative contact tracing events.

Advantages of the systems and methods described herein include enhancedspeed and accuracy of contact tracing in the shipboard context, and theability to implement narrowly-tailored quarantines in lieu of ship-widequarantines. Public health policies that are currently implemented inthe event of a communicable disease in the shipboard context typicallyimpose a ship-wide quarantine of all guests and crew members that arephysically present on a particular cruise ship associated with acurrently-embarked or previously-embarked index case. Such ship-widequarantines have been demonstrated to increase, rather than reduce, thecommunication of infectious disease within the ship. In implementationsof the present disclosure, individuals who are identified as “closecontacts” (either by direct association with the index case asdemonstrated by recorded contact tracing events, proximate movementprofiles or by indirect association with the index case via anintermediary close contact) can be quickly isolated usingnarrowly-tailored person- or group-specific quarantines. Individuals whoare not identified as “close contacts” can be isolated from “closecontacts” by, for example, rapid disembarkation from the ship orisolation in a particular area of the ship. If appropriate or requiredby public health officials, such individuals who are not subject toperson- or group-specific quarantines onboard the ship canself-quarantine for a period of time following disembarkation from theship, without experiencing days, and in some cases weeks, of increasedrisk of exposure to the infectious disease onboard the ship.

Implementations of the present disclosure can give the ship'sleadership, such as the captain and the medical officer, the ability toperform contact tracing without the use of outside resources, such asshoreside resources. Because embodiments of the present disclosureprovide ship operators with ship-initiated and ship-implemented contacttracing, valuable time is not lost while the ship waits for shoresidecontract tracing resources. The data-driven nature of contact tracingaccording to the present disclosure also results in a highly accuratelist of close contacts. This enables the ship's leadership to implementnarrowly-tailored quarantine measures onboard as soon as a single indexcase is identified, and to report to each port of call or healthauthorities as may be necessary. Shoreside employees of the cruiseoperators may, in some cases, access information generated by thesystems and methods described herein, for example to view reports,or—should the need arise—to run the reports shoreside.

Systems for Collecting Location Data

Systems and methods of the present disclosure include systems configuredto collect data on the location of a person within a bounded space suchas a cruise ship, hotel, stadium, office building or airport, to name afew examples. The data pertaining to the location of a person can beobtained using object location and tracking systems, imaging systemsconfigured to obtain image or video files, other location trackingtechnologies, or a combination of these technologies.

FIG. 1 illustrates a diagram of an example networked computing system100 within which the contact tracing systems and methods describedherein may be implemented. The system 100 includes a ship-basedcomputing system 102 which may be in communication with a shore-basedcomputing system 104 via a cloud-based or wireless network 110,according to this exemplary embodiment. In some embodiments, theship-based computing system 102 is located on a ship 101 (or other masstransport, such as a train, a shuttle, a bus, a plane, and so forth)configured to transport a plurality of individuals (e.g., users ofmobile devices such as guests, crewmembers, or others) during a trip orvoyage. The ship-based computing system 102 may include any number ofindividual independent and/or networked computing devices located withinthe ship 101, such as user computing devices 106. The shore-basedcomputing system 104 is located in a shore-based facility 103 and isassociated with a service provider, such as a company or entity thatoperates the ship 101. Alternatively, or additionally, the shore-basedcomputing system 104 may include a cloud-based database or data store108 with which the ship-based computer system 102 communicates at leastperiodically while in port or at sea. Alternatively or in addition, theshore-based computing system 104 may include a cloud-based computingsystem with which the ship-based computer system 102 communicates atleast periodically.

The system 100 may also include a plurality of user computing devices106 that are operated by customers and/or agents of the service provider(e.g., any person present within the defined environment such as theship 101 such as a guest or crewmember). The user computing devices 106may include any one of a wearable device (e.g., a dedicated wearabledevice for contact tracing and/or a wearable device configured forfunctions such as access credentialing and/or purchasing or accessingservices or products), a smartphone, a tablet, a laptop, a desktop, apersonal digital assistant (PDA), a vehicle communication system, asmartwatch, or any other electronic device. The user computing device106 allows for the determination of contact tracing events and/orlocation data points for a user 105 (for example, the guest orcrewmember, as described above) based on the user's movements and/orproximity to other users 105 while the user 105 is embarked on the ship101 during a sailing. Any suitable communications arrangement can beimplemented in embodiments of the present technology.

The shore-based computing system 104 and/or the ship-based computingsystem 102 can also store data relating to each user that is embarked onor has sailed on a particular sailing. User-specific data can include,but is not limited to, contact tracing events and/or “close contacts”determined based on contact tracing events.

FIG. 2 schematically illustrates an example system 200 for tracking ofshipboard pathogen transmission in accordance with the presenttechnology. The system 200 may be, for example, the ship-based computersystem 102 of FIG. 1 or a portion thereof. The system 200 includes adata center 202, including a server 204 and a data store 206, as well asone or more wireless access points 208 and a plurality of user devices210 (e.g., user devices 210 ₁, 210 ₂, . . . 210 _(N)).

The data center 202 can include one or more computing devices, includingat least a server 204 and a data store 206. The server 204 is configuredto communicate via wired and/or wireless communications, directly orindirectly, with any or all of the wireless access points 208. Theserver 204 and/or one or more other computing devices of the data center202 are configured to perform various processing, analysis, and/orstorage operations as described herein. The data store 206 storescontact tracing event records and/or close contact records based atleast in part on data uploaded from the user devices 210 via thewireless access points 208. In some embodiments, the data store 206stores user information for individual users (e.g., guests, crewmembers,or others) such as user identifiers, travel party information, itineraryinformation, user movement profile information, interaction information,contact tracing event records associated with individual users, and/orclose contact records associated with individual users.

The server 204 may be configured to receive contact tracing eventrecords and/or close contact records from the wireless access points 208on a continuous or periodic basis and to cause the received contacttracing event records and/or close contact records to be stored in thedata store 206 in association with user information stored therein. Forexample, a received contact tracing event record or close contact recordmay have been generated at a first user device associated with a firstuser, and may include an identifier of a second user device associatedwith a second user that was detected within a threshold distance. Inresponse to receiving the record, the server 204 can cause the record tobe stored in the data store 206 in association with both the first userand the second user.

In order to avoid duplicate records in the event that the second user'suser device also recorded a contact tracing event record or closecontact record based on the same interaction, the server 204 can furtherperform deduplication of records. For example, the server 204 maydetermine not to cause an additional record to be stored, based on therecord from the first user device, if a record of interaction with thesecond user device already exists for the first user device with anoverlapping timestamp (e.g., based on a previously received record fromthe second user device). In some embodiments, upon detection of aduplicate record, the server 204 may alter the preexisting record suchas by changing the total duration of the recorded contact tracing event.For example, if the timestamp ranges of the two duplicate events overlapbut are not identical, the server 204 may record the full union of thetwo timestamp ranges as the duration of the contact tracing event. Insome cases, this implementation of the union function may cause anexisting contact tracing event record, which was of insufficientduration to be considered a close contact, to be converted to a closecontact record if the union of the two timestamp ranges is greater thanthe close contact time threshold.

The wireless access points 208 may be disposed at various locationsthrough the ship or other defined environment where they may detect andcommunicate wirelessly with user devices 210. In some embodiments, thewireless access points 208 may be strategically placed so as to increasethe probability of contacting most or all of the user devices 210. Forexample, in a cruise ship implementation, wireless access points 208 maybe placed in common areas where many guests and crewmembers pass orcongregate. In one example, at least some wireless access points 208 maybe placed in corridors leading to staterooms, in corridors leading tocrew accommodations, in dining facilities, and the like. In anotherexample, a wireless access point 208 may be placed at or near eachlocation on the ship where guests and crewmembers can disembark.

The wireless access points 208 may be configured with any one or morewireless communication protocols suitable for communicating with theuser devices 210 and/or other devices. For example, the wireless accesspoints 208 may be configured to communicate with the user devices 210using any one or more of Bluetooth, Bluetooth Low Energy (BLE), Wi-Fi,RFID, or other suitable wireless communication protocol. In someembodiments, the wireless access points 208 are dedicated wirelessaccess points 208 for a contact tracing system (e.g., BLE devicesconfigured to communicate with the user devices 210 via BLE). In otherimplementations, the wireless access points 208 may be multi-functiondevices. For example, the wireless access points 208 may be configuredto communicate with the user devices 210 via BLE while also beingconfigured to provide other wireless access services such as a localarea wireless network for internet access.

Each wireless access point 208 can include a wireless communicationinterface, one or more processors and one or more memory devicesincluding computer-executable instructions that cause the one or moreprocessors to detect individual user devices 210 within a suitable rangefor reliable data transmission and, upon detection, to cause theindividual user devices 210 to upload contact tracing event recordsand/or close contact records stored thereon. The one or more memorydevices can further be configured to store the records uploaded from theuser devices 210 at least until the records are transmitted to the datacenter 202. In various embodiments, the wireless access points 208 cantransmit the received records to the data center 202 immediately uponreceipt from the user devices 210, or may be configured to store thereceived records locally and transmit a larger set of received recordsto the data center 202 when a threshold number of records is reachedand/or at a specified time according to a predetermined upload schedule.

The user devices 210 are mobile devices configured to be carried byindividual users throughout the predetermined environment. In someembodiments, the user devices may be dedicated contact tracing userdevices, for example, wearable devices such as wristbands, neck worndevices, or the like. Wristbands may be especially suitable for contacttracing implementations, as a single-use wristband may be worn at alltimes during a sailing (e.g., over a duration of several days, up to twoweeks or longer) without inconveniencing the wearer. Alternatively, insome embodiments the user devices 210 may be personal computing devicessuch as smartphones or tablets having an application executing thereonthat causes the personal computing device to perform the functions ofthe user device 210 described herein. In some embodiments, the userdevices 210 may be ruggedized (e.g., waterproof, water resistant, etc.).The user devices 210 may be rechargeable, and/or may be designed asrelatively low-energy devices having sufficient battery life to operatefor the duration of a sailing without needing to be recharged, so as tofacilitate reliable operation of the devices throughout the sailing andto avoid barriers to user compliance and participation.

In cruise ship implementations, the system 200 may include a largenumber of user devices 210 (e.g., up to hundreds or thousands of userdevices 210). The system 200 may include a suitable number of userdevices 210 such that a user device 210 is issued to every user aboardthe ship (e.g., every person, every adult, or every person above athreshold age, including both guests and crewmembers).

FIG. 3 schematically illustrates an example user device 210 configuredfor tracking of shipboard pathogen transmission in accordance with thepresent technology. The user device 210 includes at least a mass storagedevice 212, a processor 214, a memory 216, and a wireless communicationmodule 218. The memory 216 can store computer-executable instructionsthat, when executed by the processor 214, cause the processor to detectother user devices 210 nearby using the wireless communication module218. The wireless communication module 218 may be configured for anysuitable wireless communication protocol, such as Bluetooth, BLE, RFID,Wi-Fi, or the like.

When another user device 210 is detected (e.g., based on wirelesscommunications between the wireless communication module 218 and thewireless communication module 218 of a nearby second user device 210),the processor 214 may implement one or more algorithms stored in thememory 216 to generate contact tracing event records and/or closecontact records based on the wireless communications between the twouser devices 210. The processor 214 can further cause the generatedcontact tracing event records and/or close contact records to be storedin the mass storage device 212.

The wireless communication module 218 is further configured to detectand communicate with wireless access points 208 (FIG. 2). Based ondetecting a wireless access point 208, the processor 214 is configuredto cause the wireless communication module 218 to transmit contacttracing event records and/or close contact records from the mass storagedevice 212 to the wireless access point 208. In various embodiments, theuser device 210 may be configured to transmit the records stored in themass storage device 212 each time a wireless access point 208 isdetected, or may selectively transmit the records on a time-basedschedule. For example, when a wireless access point 208 is detected, theuser device 210 may be configured to transmit stored records only if aperiodic interval (e.g., 1 minutes, 5 minutes, 10 minutes, 30 minutes, 1hour, 2 hours, 6 hours, 12 hours, 24 hours, or any other suitablethreshold time) has elapsed since the most recent upload of records to awireless access point 208. In another implementation, a time-basedschedule may be implemented by programming the user device 210 to stopsearching for wireless access points 208 after each upload, and toresume searching and/or detecting wireless access points 208 after theperiodic interval elapses.

After each upload to a wireless access point 208, the uploaded recordsmay be retained within the mass storage device 212 or may be erased. Insome embodiments, the user device 210 may be configured to upload onlythe records that were stored subsequent to a timestamp associated withthe most recent upload. In the event that a user device 210 storesenough contact tracing event records to exceed the storage capacity ofthe mass storage device 212, the processor 214 may be configured toerase or overwrite the oldest stored records in order to store newcontact tracing event records as they are recorded.

Data Collection Using Object Location and Tracking

In one example implementation, an infectious disease tracking system ofthe present disclosure includes a plurality of wireless access pointsdisposed within a cruise ship. Each wireless access point of theplurality of wireless access points includes a communication moduleconfigured to detect and identify mobile devices in proximity to thewireless access point. Each wireless access point of the plurality ofwireless access points also includes a processor in communication withthe communication module. The processor is configured to cause storage,in a data store, of a location data point each time a mobile device isdetected. Example mobile devices include, but are not limited to, apersonal computing device and a wearable electronic device. In onenon-limiting example, all individuals embarked on a cruise ship arerequired to wear a personal electronic device during the time individualis embarked on the cruise ship. Such personal electronic devices can bedistributed at the time of embarkation and collected at the time ofdebarkation. In another example, such personal electronic devices can bedistributed when an individual onboard a voyage, or animmediately-preceding voyage, is identified as an index case

Each location data point includes a timestamp, an association with thewireless access point, and an association with a user corresponding tothe mobile device. The user can include, for example, a guest orcrewmember onboard the cruise ship. The communication module of eachwireless access point can be configured to detect and identify mobiledevices using one or more of near Bluetooth, Bluetooth Low Energy (BLE),near-field communication (NFC), Wi-Fi, radio-frequency identification(RFID), or a wireless broadband communication protocol.

One of the main concerns with implementing such technology on a ship isthat BLE/RFID technology bleeds from deck to deck on ships as opposed toapartment buildings, given the proximity of the access points and thethin layer materials used in shipbuilding. So it may be necessary toisolate and discard signals that are coming from other decks. In otherwords, a guest walking through a hallway on Deck 5 may be picked up by aBLE Access Point in Deck 4, but technology solutions are described inU.S. Pat. No. 10,645,536 that help solve this problem. Example systemsand methods for object location and tracking that can be implemented inthe present disclosure are described in U.S. Pat. No. 10,645,536, whichis incorporated herein by reference in its entirety.

Data Collection Using Facial Recognition Systems

Data pertaining to the location of a person can be obtained using facialrecognition systems. For example, an imaging system including cameraslocated throughout the ship can be configured to determine facialrecognition results based on images captured by the imaging system. Insome cases, images and video files obtained by the imaging system areused to identify that a particular individual, such as a guest or crewmember, is present at a particular location within the cruise ship.Implementations of the present disclosure can use this locationinformation to develop a movement profile corresponding to a particularindividual of interest, such as an index case or individuals who mayhave come in close contact with the index case.

Advantageously, embodiments of the present disclosure can be implementedusing just facial recognition technology because such technologycurrently covers most public spaces onboard a cruise ship. For example,cruise operators using computer vision technology can recognize guestsin dining rooms and other generally crowded areas, such as a casino.Also, stateroom doors equipped with facial recognition technology, suchas that described in U.S. Pat. No. 10,776,613, can provide facialrecognition results in hallways. Although facial recognition would belimited to public area locations like the pools, casinos, restaurants,promenade, and hallways, a single movement profile can be accurately andeffectively stitched together using facial recognition results from suchpublic areas.

Example systems and methods for object location and tracking that can beimplemented in the present disclosure are described in U.S. Pat. No.10,776,613, which is incorporated herein by reference in its entirety.

Data Collection Using Object Location and Tracking and FacialRecognition Systems

Implementations of the present disclosure can process data collectedfrom both objection location and tracking systems and facial recognitionsystems to develop a movement profile of an individual of interest, suchas an index case or individuals who may have come in close contact withthe index case.

In an example implementation, an infectious disease tracking system ofthe present disclosure includes an imaging system disposed within acruise ship. The imaging system can record images or video of areas ofthe cruise ship, including areas where the plurality of wireless accesspoints are located. The imaging system can be configured to determinefacial recognition results based on images captured by the imagingsystem. The infection disease tracking system can include a serverconfigured to obtain, from the imaging system, an image or video filecorresponding to a location data point that is indicative of a possiblecontact with an index case. The index case's movement profile caninclude, for example, the location data point. The server is alsoconfigured to store an association between each image or video file anda user associated with the location data point that is indicative of thepossible contact with the index case. The infectious disease trackingsystem can be configured to determine, based on the stored association,a set of individuals who may have come into contact with the index case.Such facial recognition results can also be used to enhance or increaseconfidence of location data obtained using object location and trackingsystems.

Example Contact Tracing Implementations

Various example implementations of contact tracing methods based on thedata collection systems of the present technology will now be described.

Contact Tracing Based on Detected Contact Tracing Events

FIG. 4 is a flow chart illustrating an example algorithm 400 forrecording contract tracing event records and/or close contact records inaccordance with the present technology. The algorithm 400 may beperformed by any suitable computing device in the possession of a user.For example, the algorithm 400 may be implemented by any of the userdevices 210 described with reference to FIGS. 2 and 3. In the context ofthe system 200 of FIG. 2, many or all of the user devices 210 ₁, 210 ₂,. . . 210 _(N) may each be configured to perform the algorithm 400 whenthey detect other user devices 210 nearby. In one particular exampleimplementation, each of the user devices 210 is a Bluetooth Low Energy(BLE) enabled wearable device such as a wristband, worn by every guest(or every guest above a threshold age) and crewmember aboard a cruiseship. However, it will be understood that the algorithm 400 is notlimited to this particular implementation.

The algorithm 400 begins at block 402 when another user device 210 isdetected. For example, the wireless communication module 218 (e.g., aBLE communication device) of a first user device 210 may establishcommunication with the wireless communication module 218 of a seconduser device 210 within a suitable signal range (e.g., by continuouslylistening for other nearby devices). Based on detecting one or moresignals from the wireless communication module 218 of the second userdevice 210, the processor 214 of the first user device 210 can beginexecuting the algorithm 400. In some cases, if both the first and seconduser devices 210 detect each other, both devices may begin executing thealgorithm 400 simultaneously. When a second user device 210 is detected,the algorithm 400 continues to decision state 404.

At decision state 404, the processor 214 determines whether a strengthof the signal received from the second user device 210 is greater thanor equal to a first predetermined threshold (e.g., an event initiationsignal strength threshold, referred to hereinafter as “threshold A”).Threshold A may be selected to correspond to a desired physical distancebetween the two user devices 210. For example, in some embodiments,threshold A may be selected to correspond to a distance such as 3 feet,6 feet, 10 feet, 20 feet, or any other suitable distance associated witha heightened risk of pathogen transmission. It will be understood thatsuitable physical distance thresholds may evolve based on updatedunderstandings of specific pathogen transmission times and methods,without departing from the spirit or scope of the present technology.

The event initiation signal strength threshold may be expressed in termsof a signal strength such as a Received Signal Strength Indicator (RSSI)value or other suitable unit of signal strength. The specific RSSI valueof threshold A may be determined empirically for a set of user devices210, for example, by measuring signal strength between two sample userdevices 210 worn by users placed at the desired physical distancethreshold. In one particular example, a set of user devices 210 may usea threshold such as −68 decibel-milliwatts (dBm) or other suitablevalue, as threshold A. Empirical adjustment of threshold A may bedesirable to avoid false negatives, in which two users come close enoughto transmit a pathogen, without their user devices 210 recording acontact tracing event record. In some embodiments, threshold A can beset low enough such that signal attenuation by the human body does notunduly prevent the generation of contact tracing event records.

If the signal strength is not greater than or equal to threshold A, thealgorithm 400 terminates at block 406, and a contact tracing event isnot recorded. If the signal strength is greater than or equal tothreshold A, the algorithm 400 continues to block 408, where the userdevice 210 starts recording a contact tracing event. The processor 214may store, in the mass storage device 212, a new contact tracing eventrecord including an initial timestamp corresponding to a device time atwhich the detected signal exceeded threshold A. The record may furtherinclude other information such as an RSSI value of the signal, a devicelocation, and/or an identifier of the second user device 210.

After the user device 210 has started recording the contact tracingevent by establishing a contact tracing event record in the mass storagedevice 212, the algorithm 400 continues to block 410, where the userdevice 210 continues recording the contact tracing event. In someembodiments, the processor 214 continues adding data to the establishedcontact tracing event record in the mass storage device 212. Forexample, the processor may add further paired RSSI-timestamp data pointsto the record at a periodic interval while the user device 210 continuesto receive the signal from the second user device 210.

As the user device 210 continues recording the contact tracing event,the processor 214 continues to decision state 412, where it maycontinuously or periodically determine whether the signal strength isgreater than or equal to a second predetermined threshold (e.g., anevent interruption signal strength threshold, referred to hereinafter as“threshold B”), which may be the same as or different than threshold A.Threshold B may similarly be expressed in terms of a RSSI value in dBm,or any other suitable unit of received signal strength. As long as thesignal remains above threshold B, the algorithm 400 continues to recordthe contact tracing event at block 410. If the signal strength dipsbelow threshold B, the user device 210 may interrupt recording of theevent.

Threshold B may be greater than, equal to, or lower than threshold A.However, it may be advantageous to set threshold B lower than thresholdA in order to address certain shortcomings of the use of RSSI or othersignal strength indicators as a method of measuring physical distancebetween people wearing user devices 210. Specifically, water, whichmakes up a large proportion of the human body, reliably absorbsfrequencies in the 2.4 GHz range, resulting in significant signalattenuation when a user's body is disposed between their user device 210and the second user device 210. Thus, it is likely that the signalstrength will drop below threshold A, at least temporarily, one or moretimes while the two users remain within the selected physical proximity.Accordingly, the reliability of contact tracing event recording isimproved by allowing the signal strength to drop temporarily below thethreshold A that is used to initiate recording of a contact tracingevent, without terminating the record.

If it is determined at decision state 412 that the signal strength islower than threshold B, the algorithm continues to decision state 414,where a grace period begins elapsing. The grace period is apredetermined time interval that is allowed to pass before the userdevice 210 terminates recording of the contact tracing event. While thesignal strength remains below threshold B, the processor 214 may suspendrecording of data points (e.g., paired RSSI-timestamp data points) ormay continue recording data points that include the sub-threshold Bsignal strength values. If the signal strength returns to a valuegreater than threshold B before the grace period elapses, the algorithmreturns to block 410 and continues recording the event. If the graceperiod elapses without the signal strength returning to a value abovethreshold B, the contact tracing event is terminated, and the algorithmcontinues to decision state 416.

The grace period is a predetermined time period selected to allow fortemporary periods of signal attenuation or increased distance betweenusers during a contact tracing event. For example, if two users standwith six feet of each other for a relatively long time period (e.g.,five minutes or more), but move to a greater distance (e.g., 20 feetapart) for a brief period (e.g., 30 seconds) in the middle of thefive-minute time period, it is generally understood that such momentarydistancing does not substantially reduce the probability of pathogentransmission during the five-minute time period. Thus, it is desirableto incorporate a grace period as described herein so as to reduce theoccurrence of false negative results.

When the grace period has elapsed, the contact tracing event terminatesand no additional data (e.g., paired RSSI-timestamp data points) areadded to the contact tracing event record in the mass storage device212. At decision state 416, the processor 214 determines, on the basisof the completed record, whether or not the recorded contact tracingevent should be deemed a “close contact.” To do so, the processor 214can determine a timestamp range of the terminated record, and comparethe range to a predetermined close contact time threshold. In someembodiments, the processor 214 may subtract the initial timestamp valuerecorded at block 408 from a final timestamp value (e.g., the finaltimestamp value recorded prior to the signal strength dropping belowthreshold B, the first timestamp value associated with a signal strengthbelow threshold B, or a timestamp value recorded at the end of the graceperiod when the recording is terminated). The subtracted timestamprange, corresponding to the total elapsed time of the contact tracingevent, is then compared to the close contact time threshold to determineif the event was a “close contact.”

If the timestamp range is less than the close contact time threshold,the algorithm 400 terminates at block 418, where the recording isterminated without recording a close contact. In some embodiments, thenon-“close contact” contact tracing event record may still be retainedin the mass storage device 212 and sent to the data center 202 via awireless access point 208 (e.g., for further analysis in conjunctionwith a corresponding contact tracing event record sent from the seconduser device 210). Alternatively, if the timestamp range is greater thanor equal to the close contact time threshold, the algorithm 400terminates at block 420, where the contact tracing event record isstored as a “close contact” in the mass storage device 212.

The close contact time threshold may be determined based on any desiredstandard for pathogen transmission. For example, the close contact timethreshold may be selected based on a science-based recommendation,regulation, policy, or guideline from an applicable health authority,such as the World Health Organization (WHO), the Centers for DiseaseControl and Prevention (CDC), or any other appropriate state, national,or international governmental or non-governmental organization. Exampleclose contact time thresholds may be, for example, 2 minutes, 5 minutes,10 minutes, 15 minutes, 20 minutes, or more, and it will be understoodthat suitable close contact time thresholds may evolve based on updatedunderstandings of specific pathogen transmission times and methods,without departing from the spirit or scope of the present technology.

FIG. 5 is a flow chart illustrating an example method 500 for contacttracing in accordance with the present technology. The method 500 may beperformed by any suitable pathogen transmission tracking system. Forexample, the method 500 may be performed at least partially by thesystem 200 of FIG. 2 including a data center 202, a plurality of userdevices 210, and wireless access points 208 configured to communicatewith the data center 202 and the user devices 210. In one particularimplementation, the system 200 is at least partially disposed within acruise ship and each of the user devices 210 is a BLE enabled wearabledevices such as a wristband, worn by every guest (or every guest above athreshold age) and crewmember aboard a cruise ship. However, it will beunderstood that the method 500 is not limited to this particularimplementation.

The method 500 begins at block 502, which may coincide with theintroduction of a plurality of users to a specified environment. Forexample, the method 500 may begin at block 502 when guests andcrewmembers board a cruise ship. In some embodiments, the method 500 maybe initiated as the first crewmembers board the ship, and additionaluser devices 210 may subsequently be added to the system 200 asadditional crewmembers and the guests embark.

At block 504, one of the wireless access points 208 connects to one ofthe user devices 210. As described elsewhere herein, the user device 210and the wireless access point 208 may connect using any suitablewireless communication protocol, such as Bluetooth, BLE, Wi-Fi, RFID, orthe like. The user devices 210 may be configured to initiate theconnection at block 504 on a periodic basis and/or based at least inpart on detecting a wireless access point 208 within range.

After the wireless access point 208 and the user device 210 establish awireless data connection, the method 500 continues to block 506, wherethe wireless access point 208 receives an upload of one or more contacttracing event records from the user device 210. Some or all of thecontact tracing event records may be indicated as “close contacts.” Atblock 508, the wireless access point 208 causes storage of the contacttracing event records. The wireless access point 208 may at leasttemporarily store the uploaded contact tracing event records in aninternal memory of the wireless access point 208 and/or may transmit thecontact tracing event records to the data center 202, where the server204 may cause the contact tracing event records to be stored in the datastore 206. The wireless access point 208 returns to block 504 andcontinues connecting to in-range user devices 210, repeating blocks 504through 508 repeatedly (e.g., until the end of a sailing, until theusers leave the specified environment, etc.).

As uploaded records are stored in the data store 206, additionalprocessing and/or organization may be performed. In one example, eachuploaded record may be stored in the data store 206 in association withboth the user of the first user device 210 that generated the record,and in association with the user of the second user device 210 thatinteracted with the first user device 210 to cause the record to begenerated. In some embodiments, all contact tracing event records areretained. Alternatively, only the “close contact” records may beretained in association with the corresponding users. In anotherexample, deduplication may be performed so as to remove duplicaterecords of the same contact tracing event (e.g., records generated byboth user devices 210 in an event). As discussed above, deduplication ofrecords can further include determining a final duration of thededuplicated event based on a union function of the two timestamp rangesof the records. Moreover, in some embodiments, the determination ofwhich contact tracing event records are “close contacts” (e.g., decisionstate 416 of FIG. 4) may be performed by the processor 214 rather thanat the user device 210 prior to upload.

At block 510, an index case may be identified. For example, in a cruiseship implementation, a user (e.g., a cruise ship guest or crewmember)may be identified as having a communicable disease. The disease may bedetected during the sailing while the users are still within the ship,or may be detected subsequent to the sailing after the users havedisembarked. In order to perform effective contact tracing for theperiod during with the index case user was aboard the ship, the contacttracing event records stored in the data store 206 may be used toidentify the other users who were in close contact with the index case.

At block 512, a set of index case close contacts is determined. Forexample, the processor 204 may query the data store 206 to identify allof the close contact records stored in association with the index caseuser. Based on the identifiers of the other user devices 210corresponding to each close contact record, the processor 204 may thengenerate a list of all other users who were involved in a “closecontact” with the index case user. In some embodiments, the processor204 may further determine any additional users (e.g., those additionalusers identified in close contact records with the index case closecontacts subsequent to their close contact with the index case and/orafter a predetermined incubation period) as secondary close contacts. Atblock 514, the list of “close contact” users, as well as any optionallisting of secondary close contacts, is output, such as for notificationand/or treatment of the close contacts and/or secondary close contacts.

Contact Tracing Based on Movement Profiles

As described above, a large number of location data points may becollected and stored for each user aboard a vessel. Accordingly, theselocation data points may advantageously be used in conjunction with anidentified index case to identify others aboard the vessel that may havecome into contact with a known pathogen.

In an example contact tracking implementation, one of the users (e.g.,current or recent passengers or crew aboard a vessel, as describedabove) may be identified as an index case. In order to prevent furthertransmission of the pathogen, it may be desirable to identify a set ofusers that should be quarantined, for example, due to having beenpotentially in contact with the index case. It may similarly bedesirable to identify a group of users who have not been in contact withthe index case or with those who have been in contact with the indexcase, such that the non-exposed users may leave the vessel beforepossibly being exposed.

In some embodiments, when an index case is identified, an identificationof the index case is provided to a server of an infectious diseasetracking system on the vessel. The index case is preferably one of themany mobile device users aboard the vessel or previously aboard thevessel. The identification provided to the server may be, for example, aname, identification number, or other identifier uniquely correspondingto the individual user determined to be the index case.

In response to receiving the identification of the user determined to bethe index case, the server can begin a contact tracing process toidentify possible pathogen transmission paths. The server firstdetermines a movement profile corresponding to the index case. In someembodiments, determining the movement profile may include collecting orobtaining from a data store all of the location data points associatedwith the index case. For example, the server may obtain from the datastore all of the location data points that include an association withthe index case user. In some cases the set of location data pointsassociated with the index case may be ordered in a chronological order.

One or more additional movement profiles may further be determined. Insome embodiments, the infectious disease tracking system may determine,based on the initial identification of the index case, that the vesselhas an “infected” status, and may initiate the generation of movementprofiles corresponding to all users aboard the vessel. In otherembodiments, the infectious disease tracking system may generatemovement profiles for only a subset of the users aboard the vessel, forexample, to better utilize available computing resources. The subset maybe determined, for example, by a “first-pass” method that selects userswho may have come into contact with the index case, and only generates afull movement profile for each user in the subset.

In one example, the server determines a first set of contacts based onthe location data points in the movement profile of the index case. Theserver may retrieve additional data stored by the wireless accesspoints, and may identify, for each location data point in the index casemovement profile, all of the additional location data points generatedby the same wireless access point within a threshold time around thetimestamp of the location data point (e.g., all location data pointsgenerated by the same wireless access point and having a timestampwithin 10 seconds, 20 seconds, 30 seconds 1 minute, etc., of the indexcase location data point). The time threshold may be selected (e.g., bya medical officer or other crew member) based on specific transmissioncharacteristics of the particular pathogen or disease. The timethreshold can be selected based on guidance provided by public healthofficials. The server or other component of the system may generate areport or list including the names, identifying information, and/orother identifiers of all of these secondary users associated with any ofthe identified additional location data points. A movement profile maybe generated for each secondary user in the list by the same process asdescribed above for generating the movement profile for the index case.

In some embodiments, one or more additional close contacts (e.g.,secondary users determined to have come into contact with the indexcase) may be determined based on other criteria outside of objecttracking and location. For example, family members staying in the samestateroom as the index case, family members of the index case staying indifferent staterooms, and/or other travelers known to be acquainted withthe index case based on having linked itineraries or reservations may bedetermined to be among the secondary users. Similarly, family membersstaying in the same stateroom as a secondary user, family members of asecondary user staying in different staterooms, and/or other travelersknown to be acquainted with a secondary user based on having linkeditineraries or reservations may be determined to be among the secondaryusers or tertiary users who have come into contact with secondary users.

In some embodiments, a similar comparison and time thresholding approachmay further be implemented to identify the set of additional or tertiaryusers who may have come into contact with the secondary users. Thisadditional identification may be desirable as it allows for theidentification of those users who have not been in close contact withthe index case but who may have been exposed to the pathogen by cominginto contact with a secondary user who did contact the index case.

When the set of secondary and/or tertiary users has been determined, theinfectious disease tracking system may generate one or more lists suchas a quarantine list (e.g., including the index case, the secondaryusers who are determined to have potentially come into close contactwith the index case, and optionally the tertiary users who aredetermined to have potentially come into close contact with thesecondary users) and/or a list of non-exposed users who may be allowedto leave the vessel (e.g., including all passengers and crew who aredetermined not to have come into contact with the index case and/or withany of the secondary users).

In some embodiments, the system may take one or more additional actionsin addition to generating the lists of exposed and non-exposed users asdescribed above. For example, in some embodiments the system may furtherbe configured to identify surfaces located along or near the movementprofile of an index case or of a secondary user, such that a cleaningcrew can quickly be dispatched to disinfect those areas. For example, ifa movement profile indicates that a passenger, after being exposed to apathogen, visited a restaurant, bar, swimming pool, lounge area, orother area where the passenger may have stopped and touched one or moresurfaces, those areas may be identified based on the passenger'smovement profile and cleaned thoroughly to avoid transmission of thepathogen to others. In some embodiments, exact surfaces touched by anindex case or by secondary users may be pinpointed, for example, basedon video or still images obtained from a CCTV or other imaging systemthat monitors the areas identified within the movement profile.Accordingly, the systems and methods of the present technology canadvantageously mitigate transmission both by person-to-person contactand by secondary surface transmission.

Implementations of the present disclosure can advantageously performcontact tracing for guests currently embarked on a voyage even insituations where the index case is identified after the index case hasdisembarked. The infectious disease tracking system can retain locationdata points associated with a particular voyage in the data store for apredetermined retention period. The predetermined retention period canbe temporal (for example, a period of two weeks or one month) orvoyage-based (for example, for the duration of the next voyage or theduration of the next two voyages). In one non-limiting example, a cruiseoperator may learn during Voyage B of Ship X that a guest embarked on animmediately preceding voyage, Voyage A, of Ship X is an index case. Inimplementations of the present disclosure, contact tracing can beperformed for all guests and crewmembers that were embarked on Ship Xduring Voyage A (using location data points stored in the data storeduring Voyage A and retained in the data store for the predeterminedretention period), and for all guests and crewmembers that are currentlyembarked on Ship X during Voyage B (using location data points stored inthe data store during Voyage B). Accordingly, embodiments of the presentdisclosure can perform backward-looking contact tracing to identifyindividuals that came in close contact with an index case during a priorvoyage. This is particularly advantageous in situations where theindividual that came in close contact with an index case during a priorvoyage did not debark the ship at the end of the prior voyage. Returningto the prior example, an individual who came in close contact with anindex case during Voyage A may not have debarked Ship X at the end ofVoyage A, but continued her stay on Ship X during Voyage B. If thisindividual contracted the disease during Voyage A from the index case,the individual may be actively transmitting the infectious disease toguests embarked on Ship X during Voyage B, depending on the incubationperiod of the disease and other factors. Rapid and accurate contracttracing across multiple voyages is particularly advantageous in cases ofa novel disease with an uncertain or unknown incubation period.

Further Example Embodiments

1. An infectious disease tracking system for a cruise ship, the systemcomprising:

-   -   a plurality of wireless access points disposed within the cruise        ship, each wireless access point of the plurality of wireless        access points comprising:        -   a communication module configured to detect and identify            mobile devices in proximity to the wireless access point;            and        -   a processor in communication with the communication module,            the processor configured to cause storage, in a data store,            of a location data point each time a mobile device is            detected, each location data point comprising:            -   a timestamp;            -   an association with the wireless access point; and            -   an association with a user corresponding to the mobile                device; and    -   a server in communication with the data store, the server        configured to:        -   receive an identification of a first user determined to be            an index case of a disease;        -   determine, based on the timestamps and the wireless access            points corresponding to a plurality of location data points            associated with the first user, a movement profile            corresponding to the first user;        -   identify, based on the movement profile, one or more            additional location data points indicative of a possible            contact with the first user, each of the one or more            additional location data points associated with a user other            than the first user; and        -   determine, based on the one or more additional location data            points, a set of second users who may have come into contact            with the first user.

2. The infectious disease tracking system of Embodiment 1, wherein theserver is further configured to determine movement profilescorresponding to the second users.

3. The infectious disease tracking system of Embodiment 2, wherein theserver is further configured to determine, based at least in part on themovement profiles corresponding to the second users, a set of thirdusers who may have come into contact with one or more of the secondusers.

4. The infectious disease tracking system of Embodiment 3, wherein theserver is further configured to generate, based at least in part on theset of second users, the set of third users, and a passenger manifest ofthe cruise ship, a list of passengers who have not come into contactwith the first user or the one or more other users who have come intocontact with the first user.

5. The infectious disease tracking system of Embodiment 3, wherein theserver is further configured to generate, based at least in part on theset of second users and the set of third users, a list of passengers tobe quarantined.

6. The infectious disease tracking system of Embodiment 1, wherein eachof the mobile devices comprises one or more of a personal computingdevice or a wearable electronic device.

7. The infectious disease tracking system of Embodiment 1, wherein thecommunication module of each wireless access point is configured todetect and identify mobile devices using one or more of near Bluetooth,Bluetooth Low Energy (BLE), near-field communication (NFC), Wi-Fi,radio-frequency identification (RFID), or a wireless broadbandcommunication protocol.

8. The infectious disease tracking system of Embodiment 1, wherein eachof the one or more additional location data points is identified if theadditional location data point is associated with the same wirelessaccess point and has a timestamp within a threshold time relative to atleast one of the location data points associated with the first user.

9. The infectious disease tracking system of Embodiment 1, wherein theserver is further in communication with an imaging system that recordsimages or video of areas of the cruise ship where the wireless accesspoints are located.

10. The infectious disease tracking system of Embodiment 9, wherein theserver is further configured to:

-   -   obtain, from the imaging system, an image or video file        corresponding to each of the additional location data points;        and    -   store an association between each image or video file and the        second user associated with the corresponding additional        location data point.

11. The infectious disease tracking system of Embodiment 9, wherein theimaging system is further configured to determine facial recognitionresults based on images captured by the imaging system, wherein theinfection control system is further configured to identify second usersbased on the facial recognition results.

12. The infectious disease tracking system of Embodiment 1, wherein thesystem retains the location data points in the data store for apredetermined retention period.

13. The infectious disease tracking system of Embodiment 12, wherein thepredetermined retention period is one month.

14. The infectious disease tracking system of Embodiment 12, wherein thesystem retains the location data points stored in the data store duringa first voyage of the cruise ship until at least the end of a subsequentvoyage of the cruise ship.

What is claimed is:
 1. An infectious disease tracking system for acruise ship, the system comprising: a plurality of user devices, eachuser device comprising a wireless communication module, one or moreprocessors, and memory storing computer-executable instructions that,when executed by the one or more processors, cause the one or moreprocessors to at least: detect, using the wireless communication module,a signal emitted by another one of the plurality of user devices;determine that a strength of the signal exceeds a predetermined eventinitiation signal strength threshold; store, in the memory, a contacttracing event record in response to determining that the strength of thesignal exceeds the predetermined event initiation signal strengththreshold; and transmit the contact tracing event record.